During the period that elapsed between Mr. Bancroft's withdrawal from London and Mr. Lawrence's arrival as the representative of the United States, Mr. Clayton instructed Mr. Rives, who was on his way to Paris, to stop in London and hold a conference with Lord Palmerston on the Central American question. At this date the United States was striving simply for equal rights in any waterway that might be opened through the isthmus and not for any exclusive rights. Mr. Rives declared to Lord Palmerston "that citizens of the United States had entered into a contract with the state of Nicaragua to open, on certain conditions, a communication between the Atlantic and Pacific oceans by the river San Juan and the Nicaragua lake; that the government of the United States, after the most careful investigation of the subject, had come undoubtedly to the conclusion that upon both legal and historical grounds the state of Nicaragua was the true territorial sovereign of the river San Juan as well as of the Nicaragua lake, and that it was, therefore, bound to give its countenance and support, by all proper and reasonable means, to rights lawfully derived by their citizens under a grant from that sovereign." He further said: That the United States would not, if they could, obtain any exclusive right or privilege in a great highway, which naturally belonged to all mankind, for they well knew that the possession of any such privilege would expose them to inevitable jealousies and probable controversies which would make it infinitely more costly than advantageous; that while they aimed at no exclusive privilege for themselves, they could never consent to see so important a communication fall under the exclusive control of any other great commercial power; that we were far from imputing to Her Britannic Majesty's government any views of that kind, but Mosquito possession at the mouth of the San Juan could be considered in no other light than British possession, and his lordship would readily comprehend that such a state of things, so long as it was continued, must necessarily give rise to dissatisfaction and distrust on the part of other commercial powers.[151] The negotiations thus opened by Mr. Rives were continued by Mr. Lawrence upon his arrival in England, but were shortly thereafter transferred to Washington, where Mr. Clayton succeeded in arranging with Sir Henry Lytton Bulwer the terms of a convention which was signed April 19, 1850. The intention of the two governments, as declared in the preamble, was to set forth "their views and intentions with reference to any means of communication by ship canal which may be constructed between the Atlantic and Pacific oceans by the way of the river San Juan de Nicaragua, and either or both of the lakes of Nicaragua or Managua, to any port or place on the Pacific ocean."